Subject: Re: bug#6922: 23.1; Setting read-only property in an overlay has no effect

From: Marcin Borkowski <[email-masked]>
Date: Fri, 22 Jan 2016 13:58:08 +0100

On 2016-01-22, at 11:59, Lars Magne Ingebrigtsen <[email-masked]> wrote:

> Eli Zaretskii <[email-masked]> writes:
>
>> What do others think?
>
> I think read-only overlays sound kinda nonsensical, too.

Not necessarily.  This is not the same, of course, but compare Dired to
Wdired: the same text is sometimes read-only and sometimes not, and it
does make a lot of sense.

Another possible use-case: a feature like narrowing, but not making some
text invisible, but read-only instead.  (This might actually be useful,
e.g. in Org-mode.)

Of course, you could do this with text properties and not overlays, but
what I'm saying is that the assumption "it [is] strange to make certain
text read-only temporarily.  If it isn't supposed to change, it should
never change, right?" is false in general, even in current stock Emacs.

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University